Data/transcripts/4F_RBc1akC8_20241225194724.txt

[Music]
welcome to the hubman lab guest Series
where I and an expert guest discuss
science and science-based tools for
everyday
life I'm Andrew huberman and I'm a
professor of neurobiology and
Opthalmology at Stanford school of
medicine today March the 3D episode in
our sixth episode series all about sleep
with expert guest Dr Matthew Walker
during today's episode we discuss how to
structure your sleep for optimal mental
health physical health and performance
we discuss monophasic sleep schedules
which are the more typical sleep
schedule where you go to sleep at night
and then wake up in the morning so
sleeping in one bout as opposed to
polyphasic sleep schedules which are
when you sleep in two or more bouts
either at night or perhaps a shorter
bout of sleep at night and another bout
of sleep during the day we also discuss
naps including how to nap how long your
nap should be whether or not naps are
good or bad in particular whether or not
they're good or bad for you it turns out
this varies according to individual we
also discuss how your needs for sleep
and naps vary across the lifespan and we
discuss body position during sleep which
might seem excessively detailed but it
turns out that body position during
sleep is critical for ensuring that the
sleep you get is optimally restorative
as with the first two episodes of this
six episode series today's third episode
is filled with both science that is the
biology of sleep and napping and body
position and how those relate to one
another as well as practical tools that
you can use to vastly improve your sleep
before we begin I'd like to emphasize
that this podcast is separate from my
teaching and research roles at Stanford
it is however part of my desire and
effort to bring zero cost to Consumer
information about science and science
related tools to the general public in
keeping with that theme I'd like to
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huberman and now for my conversation
with Dr Matthew Walker Dr Walker welcome
back Dr huberman an absolute pleasure
let's talk about the different types of
sleep because I think most people think
of sleep as just one thing most people
sleep at night some people also nap a
topic we'll also discuss today
but turns out there are a lot of
different different types of sleep what
are the different types of sleep and
what do they do for us and um I guess
everyone's probably wondering already I
certainly am what types of sleep are we
already engaging in meaning am I
involved in or having multiple types of
sleep each night this is a fascinating
question and it comes back to something
we've discussed in a previous episode
the different stages of sleep and how
they unfold we've described that
fascinating stuff what you're already
asking though is is an incredibly sort
of subtle but relevant question how
should I be sleeping in terms of the
phases of sleep should I have one phase
should I have two phases of sleep or
should I have many phases of sleep in
some ways you can answer that question
on the basis of the lifespan because how
it is that we sleep in terms of those
chunking sessions changes as we
develop to be clear in
nomenclature I'm saying monophasic basic
polyphasic unpack that monophasic
obviously just simply means a single
phase monophasic when you say phase you
mean one bout of sleep correct so that
would be within a 24-hour period you are
having a single bout of sleep basic then
means that within that 24-hour phase you
are having two bouts of sleep and we'll
speak about how those bouts are split up
are they split up between two halves in
the middle of the night or are they
split up in terms of longer at night
Siesta like nap in the afternoon and
then we can speak about polyphasic sleep
polyphasic sleep we in sleep science
have been using for many years in the
context of infancy because there as any
new parents will know infants do not
just simply have a nice single bout of
sleep they're up they're down they're up
they're down and have many bouts of
sleep within that 24-hour period and
that's polyphasic sleep the other term
or the other application of that term
polyphasic sleep has been used more so
in the sort of interesting biohacker
movement and we can we'll come back to
that perhaps later on so how do these
different phases of sleep change across
the lifespan well we've already said
that when you're an infant and you're
first born within the first year of life
you are incredibly poly phasic and you
are probably going through wake sleep
phases every 2 hours why do you do that
why can't you just simply be born and
sleep in a monophasic way it's for at
least two reasons first an infant needs
to feed every two hours so their energy
needs and their food intake requirements
dictate that you can't sleep for very
long because you need to be awake to
feed and then you go back to
sleep Within probably the first six
months things will start to to change a
little bit but the second reason that
you are highly polyphasic when you are
first born is because your super
chiasmatic nucleus and in another
episode we spoke about this Central
master 24-hour clock that beats out your
Cadian Rhythm the rise and the fall the
wake and the sleep that has not yet
developed it hasn't been glued into
place into the brain this 24-hour clock
so the infant seemingly knows nothing
about when it's light or when it's dark
outside that just awake or sleep awake a
sleeve so that's the second reason
energy feeding needs is the first and
then an absence of yet a fully developed
24-hour clock in the brain to beat out
that beautiful dictated Rhythm by about
age one that number of phases of sleep
are starting to decrease but it's still
highly polyphasic it's not not until you
get to probably age two or three that
now you're starting to see this
consolidation of sleep what do I mean by
that sleep is now happening more
dominantly in the night phase of the
24-hour cycle and there a few abouts of
sleep during the
daytime then perhaps by the time you're
in kindergarten you may be down to just
two sleeps so now we've switched from
polyphasic sleep as infants to basic
sleep as kindergarten could you describe
that it was basic patterns I recall in
kindergarten um having nap time in the
afternoon yeah they put out these little
mats and every every kid would just kind
like roll up it's actually sounds really
nice it's one you know wouldn't and
we'll speak about how some adults do
this too but almost every kindergarten
system that I've inquired about around
the world different nations they all
have this nap time and Any teacher will
tell you if one of those children does
not nap during that period of time they
are the Loose Canon they are the live
wire and in subsequent episodes we'll
speak about exactly how sleep harnesses
and improves our emotional and mental
health and how it falls apart when we
don't so that that's how it certainly is
emerging biologically and that's how we
as a society respect that and
accommodate that
and then probably by the age of starting
school so sort of five or six now we're
starting to see fully monophasic sleep
children sleeping long bouts at night
and then being able to sustain
wakefulness during the day at that point
you have locked in your monophasic
pattern and that will continue
throughout adulthood and into old age
with a few caveats that we'll speak
about so that's how sleep sleep unfolds
in the monophasic biphasic polyphasic
sleep across the lifespan it doesn't
quite tell you however how those
different stages of sleep change across
the lifespan so I've shown you the view
of sleep across the lifespan through one
lens of the microscope if we click down
one lens and focus more deeply on the
different stages of sleep there we see a
fascinating
story in uo for the most part you are in
a sleep likee State as a fetus once you
get to a certain point of
development in utero that sleep-like
state seems to be more so something that
looks like REM sleep now it's not fully
fledged full fat REM sleep yet but it
seems to be something very much like REM
sleep I say this because in the first
episode I told you as we go into REM
sleep
and we start to as adults dream the
brain paralyzes the body so that the
mind can dream safely those kicks and
those punches and those elbows that uh a
mother will feel from the fetus seem to
be during this dream state often and I
don't want to shatter any illusions of
you start singing or you're cing and you
get these bumps and these elbows and
these legs kicking and it's beautiful it
is beautiful but it turns out that it's
probably the REM sleep state but the
muscle sort of paralysis has not yet
developed so you're getting these
electrical burst this frenetic activity
of REM sleep that we described but
you're not getting any of the blockade
of the motor output and so it expresses
itself as these kicks and these
bumps and then during the first six
months of life and at that point in the
first 6 months those infants are
sleeping anywhere between 14 to 17 hours
a day that's it's immense isn't it I
mean it's right up there if you look
across the across philogyny and you ask
which is by the way a fascinating Topic
at some point we should do a a separate
podcast on sleep across different
species because I know like me you love
you know the whole variety of sweet but
you've got elephants who will sleep as
little as 4 hours and then you've got
the little brown bat who is the rock
star of sleep and it will sleep sleep
almost 17 to 18 hours a day it nudges
out the sloth in that sense wow can I
ask you a question about that little
brown P yeah does it sleep hanging
upside down does so it can't have sleep
paralysis in its little claws so it it
will it will not have that paralysis but
it goes through the stages of sleep very
quickly and this happens with birds as
well so birds that flock on a branch
they will sleep and they sleep in some
fascinating ways what some sometimes
with one half of the brain sometimes
with both halves but then you say well
if I'm on a branch and there's this
wonderful Force called gravity
underneath me and I go into REM sleep
and I have that muscle paralysis which
they do how does that work well they
only have very brief REM sleep periods
that last just for a few seconds and
then they regain their muscle tone got
it couldn't couldn't help but ask it's
genius the Flora and the fauna I
especially that the fauna um enchant me
that much so I don't want to draw us off
course but now we know that they they
can that's why the bats don't fall
that's why the birds Don't Fall correct
um so when you are then as an infant
sleeping 14 to 17 hours what's happening
with those different stages of sleep
non-rem and REM at that point we can't
really Define and separate the different
stages of non-r because it's not yet
fully formed but we have what looks like
a REM sleep active State and a a deep
non-rem sleep passive state almost 50%
of the time that an infant a newborn is
asleep is spent in REM sleep why do I
say that with some kind of wonder in my
voice because as adults we're perhaps
down to maybe 20% of our time spent
asleep is in REM sleep but 50% of the
time when an infant is asleep they are
in rem why would this be the case and
across all species that have REM and
non-rem the time when we see REM sleep
in highest volume amount is always after
birth there is something special about
REM sleep and its function during that
early period and we now start to
understand why when you are first born
you are still going through a huge
amount of brain
maturation and the recipe for the day
there unlike when we are teenagers is
exploding the brain with synapses all of
these connections throughout the brain
what we've discovered is that REM sleep
acts as an electrical fertilizer to
stimulate the growth of these
connections within the brain it's almost
as though you could think about an
internet service provider with this huge
new neighborhood and the first call of
business is to go in and wire up each
one of those homes with these Fiber
Optic Cables that's what REM sleep is
doing and if you start to deprive and
these were studies gosh done many years
ago by Howard rthor and others if you
deprive animals of REM sleep you stunt
the developmental growth of the brain
and presumably the whole animal and the
yeah as a consequence I mean if you look
at its social behavior even just that
it's profoundly abnormal because you
don't have that REM sleep developed
brain I mention this not because there
is any causal evidence but we have seen
REM sleep deep impairments in certain
developmental
disorders such as autism as well as ADHD
I don't think there is any supportive
evidence yet to come out with a claim
that part of the trajectory underlying
those conditions is abnormalities of REM
sleep but I it's a very active area of
research so it's a fascinating time
though during infancy when you get these
huge amounts of REM sleep why because of
what we call synaptogenesis is which is
simply the creation of sinapsis
Genesis then as you move from 6 months
across the next 18 months something odd
happens Total Sleep time starts to
decrease REM sleep starts to decrease
but non-rem sleep actually increases
even though Total Sleep time is
decreasing and there's a strange peak in
lighter stage nonrem what we call stage
two nonr and those sleep spindles that I
was describing in the first episode
These bursts of electrical
activity we will speak about the role of
those sleep spindles in improving motor
skill learning and we've done a many
many years of work in this area why is
that relevant to this phase of life
that's right around the time when
infants start to coordinate their limbs
in a skilled way and begin to walk and
we believe that it is part of the
process of the development of the motor
system enabling walking to begin amazing
so then things will change further sleep
time continues to decrease and by about
age five or six now the cocktail blend
of nonrem and REM is down to a stable
ratio that will remain throughout the
lifespan which is a 4:1 ratio so about
20% of the time that you're asleep will
be REM sleep and the remaining time time
will be 80% of that time will be non-rem
sleeping provided one is getting
sufficient total amounts of sleep
correct and getting it at the right
moments in time that we described in the
first episode getting that sort of that
appropriate chronotype match to the
24-hour clock that will certainly alter
those things too so that's how sleep
unfolds both at the first level of the
lens monophasic basic polyphasic and
then double clicking how the different
stages of sleep unfold and what the
reasons are behind that I then said once
we're adults we become
monophasic yes to a degree but there is
some contention about the way that we
sleep in modernity that we may not be
sleeping in the way that we were
designed to sleep which brings us back
to basic sleep in the first episode we
spoke about this strange after afternoon
dip in our alertness that happens called
the postprandial dip and it happens
somewhere between the 1 to 4:00 p.m.
region and it's measurable and it seems
to be biologically wired into
us if you look at certain cultures that
are not touched by modernity so we and
others have studied studied hunter
gatherer tribes they don't quite sleep
the way that we do and they don't sleep
the way that we do for at least two
reasons the first is that they will
often have a siesta like pattern of
behavior where especially in the hot dry
season they will take a nap in the
afternoon in the wet cooler season that
may not be the case but they certainly
have more of a basic pattern where
they'll sleep longer at night and then
have a short nap Siesta like and then of
course there are Latin and Mediterranean
cultures and they have this practice of
the Siesta like Behavior coming back to
the hunter gather tribes the way that
they also do not sleep in a similar
manner to that which we do is the timing
of sleep they don't go to sleep as the
sun goes down they will usually on
average as a group they will usually go
to sleep about 2 hours after Sundown and
then they will wake up not with the
rising of the sun they wake up just
before that and you think how are they
predictive of the light no the thing
that changes first before the sun truly
Rises is
temperature and temperature is a very
strong predictor that forces them
awake so when you think about how
they're sleeping then consider the term
midnight most of us never really think
about what the term means midnight
refers to the fact that it is the middle
of the night but for most of us in the
modern world that's the time when we're
thinking about sending our last email or
posting to social media midnight is no
longer midnight for society but it is
for them so should we be thinking about
midnight as the middle of the night in
the context of the uh extreme early
person morning person who you know
presumably likes to go to bed around
8:00 P.M wake up around 4:00 a.m. most
people hear 4:00 a.m. and they go oh
goodness you know that's early sort of
um you know like the the mighty Joo
willink is is uh famous for posting
images of his of his uh digital watch
usually I think it's 4:30 a.m. wake up
and that's when he starts his workout so
his Twitter and I guess they call X now
feed and and Instagram is a replete with
images of his watch 4:30 and people
think goodness that's early right but he
was a guest on this podcast spoken to
him before but he goes to bed pretty
early that's right most nights so in
some sense you know midnight for him or
for somebody with a similar schedule is
truly middle of the night that's right
right but for the other chronotypes for
people that uh prefer to go to sleep or
who naturally um get sleepy around 10 or
11 p.m. or even later um how should they
think about this biphasic polyphasic
business because um at at some level um
we all have to
reconcile uh our sleep schedule with the
with the demands of work and family and
so on that's right so I was very
specific when I said the hunter gather
of tribes on average that's the way that
they will sleep but like the rest of
society there's a huge distribution and
there will be some proportion of them
who are a little bit like Joo who will
be on the early side of that on the very
early side of that but then there are
other people who are clear night owls
and they may not be going to bed until
you know 10: or 11: and waking up
later so there is a distribution there
you don't have to worry that my
statement of midnight on average that
does seem to be when we are dislocated
from all of the trappings of modernity
how a group of Representative humans on
average will sleep but there is huge as
I said differences from one individual
to the next by the way you can ask the
question why do we have these things
called chronotypes why is there such
variability in how people have a
preference for when they sleep wouldn't
it just be easier if
biology designed us all to be asleep at
the same time not so we mentioned in the
first episode that sleep is truly
idiotic in the sense that you know
you're not protecting yourself or the
people that you care about and if
everyone slept at the same moment in
time you as a collective and as an
individual would be vulnerable for an 8
hour period 7 to n hour period but by
way of this wonderful injection of
variability as to preferences for when
people sleep maybe there are some people
who are going to bed at 8:00 p.m. and
there are other people and they're
waking up at 4: a.m. there are other
people who go to bed at midnight and
wake up at 8:00 a.m. so then think about
that at some point what you've done is
that there will always be someone or
collection of people awake until
midnight and then will always be a
collection of people who are awake
starting at 4:00 a.m.
so as an individual everyone gets their
8-hour opportunity but as a collective
as a clan you are you've reduced your
vulnerability down by 50% because Mother
Nature injected the variability by way
of genetics of chronotype to distribute
that and lessen the burden does that
make any sense it does and it reminds me
of how the Circadian rhythm which we
discussed in episode one is about 24
hours not exactly 24 hours the rhythm of
the supermatic nucleus neurons that
generate the Circadian rhythm as I
recall uh is rarely exactly 24 hours
it's 24.2 or 24.4 and the idea in mind
the just so story uh is that that
variation allows for entrainment
matching to the outside light dark cycle
which changes across the year so you
don't want it rigidly 24 hours because
if there's any variation in light dark
which of course there is you know even
at the equator across the year there's
subtle variations but certainly As you
move away from the equator and so these
these uh variations in you know your
circadian rhythm uh clock scn supermatic
nucleus might be 24.2 mine might be 24.6
24 someone else
24.1 and in that sense um allows some uh
malleability to to matching the
Circadian rhythm to outside light dark
rhythms is that is that a a decent
parallel for what we're talking about
it's a beautiful demonstration that
there is always some it's almost wiggle
room in how biology is programmed
because some degree of sort of noise
almost sarcastic noise can be very
beneficial and it's much more predictive
of the way in which the world works and
it's much more adaptive for a species to
enact and to embrace that kind of
variability and yours was a beautiful
example
that it's about 24 hours but it's
certainly responsive to changes in light
duration across the year and it has to
be because we need to buckle ourselves
to the light dark cycle for optimal
survival and here is another
demonstration of where it's not about
the Cadian Rhythm but it's about the
chronotype distribution not within an
individual across the year but across
individuals at any one moment in time
and that variability once again provides
a biological
benefit in the first episode and again
now you're discussing chronotypes and
one one thing that I've been meaning to
ask is you said that chronotype is
genetically determined but that
necessarily mean it is directly
inherited from Mom Andor dad meaning if
your parents are both extreme early
morning types will you grow up to be an
extreme early morning type you already
established that during infancy and
development uh adolescence Etc that our
chronotype is somewhat masked by some of
the developmental uh um uh Necessities
um but once we reach young adulthood and
and our chronotype has been established
uh can we look to our parents to
determine whether or not we are more
likely to be in morning person or or
late shifted it's very unlikely to find
find anyone whose parents were both
extreme morning types who is a neutral
or an evening type and vice versa so my
guess is that people with if they know
of their biological parents and they
know of their rhythms it's highly likely
that you will at some point acquas in
your lifetime to being very similar to
them now there are certain life
conditions and contexts where you can
you know fight that um if you're really
into you know if you're someone who is
in punk rock band and you're touring all
the time even though your mom and dad
may be morning types and you may be a
morning type you're on the road you're
playing gigs there's no chance but at
some point let's say you retire and you
give yourself the opportunity to express
your natural Rhythm you will go back to
that so yes it's highly genetic it's not
enre highly genetic there is some degree
of modification that happens on the
basis of context and I've just given you
a good example of context and also your
exposure to light you can be someone who
is let's say a neutral like me but if
you're constantly invaded by Electric
Light at night you're drinking too much
caffeine and you're on your laptop and
your computer and your phone and you're
always activated by social media it's
very easy for someone like me to drift
and become a 1 a.m. to you know 9 a.m.
person that's not my natural type but
context and the environment have shifted
me but for the most part yes to your
question I'd like to take a brief break
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huberman okay so getting back to these
different uh phase opportunities for
Sleep uh clearly I'm getting the
language wrong here but vacular
monophasic basic and polyphasic um could
you give us a few more examples of
different types of biphasic and
polyphasic sleep so coming back to basic
sleep I describe one version once we are
adults which is the Siesta like notion
one long bout at night short bout during
the day and that bout during the day is
usually matching that drop in alertness
that we described it sort of hits that
sweet spot right there and it's quite
easy for some people to fall asleep in a
period between somewhere between one and
four 1 to four yeah and I know it's a
large window but that just allows us to
sort of know okay if you're someone like
yourself who's a morning type you would
probably start to want to nap a little
bit earli or if you were basic someone
like me a neutral probably an hour and a
half two hours later still
but there is a different version of
basic sleep for adults that has been
described in the literature and it's
fascinating but I don't think it's
biological it's the notion that some
people will have heard called first
sleep second sleep and now you are
splitting your sleep into two phases but
they're split across the night so the
idea is that you fall asleep and you'll
maybe have 4ish hours and then you wake
up and you then are awake for several
hours and then you go back to sleep for
another 3 or 4
hours if you look in history and the the
record of of human history it's very
clear that there were some cultures
doing this particularly if you look at
some of the European cultures Great
Britain in particular there is good
evidence that somewhere between about
the 15th to 19th century seems to have
ended during the kind of dezian
era people were describing this behavior
and they would wake up in the middle of
the night after about 4 hours they would
make food they would play music they
would write they would make love it was
a real thing and I'm not suggesting that
it did not happen it clearly did and
there's a there a great book that
outlines this but is it the way that we
were designed to sleep bif phasically
versus the Siesta like and I don't think
it is there is no good collection of
evidence if you look at the biology of
our human rhythms that argues that there
is this magical period of a huge spike
in Arcadian Rhythm that happens right in
the middle of the night that should
force us
awake there is one paper that's often
cited for this and in truth that paper
if you read it says nothing about first
sleep second sleep doesn't speak about
basic sleep at all
and that paper I think is unfairly used
as a justification of first sleep and
second sleep and the paper to me has at
least three problem it's a great paper
there's no no problem with the paper and
its hypothesis but its use as
justification for first sleep second
sleep has three
problems the first is the artificial
nature of the study they weren't
designing it to test the hypothesis but
they had individuals in bed for 14 hours
relative to a standard 8 hour period and
sure enough what they found was that
when you force people night after night
to be in bed for 14 hours somewhere
after about 6 or 7 hours they wake up
and then you can't get out of bed in the
study so you just lie awake and then at
some point I don't know if it's through
boredom or you drift back off into sleep
and that was argued as a clear
demonstration of this split sleep but as
I said they're awake usually for about
six and a half seven
hours also there was no magical
Awakening period it's a probability
distribution and what that means is if
you look at the data it's just more
likely that people will wake up after
about 6 or seven hours and they're more
likely that they will go back down into
sleep it wasn't as though the whole
experiment demonstrated a very clear
termination of sleep that everyone had
at that moment in time so that's the
first
issue um and the second issue which is
first issue it's kind of an abnormal
thing 14 hours forced in bed the second
is it wasn't a clear separation it's
just simply higher probability the final
issue is that it was a study done in
only seven individuals healthy males and
so I have yet to see it you know scaled
up did it happen first sleep second
sleep yes it did is there any strong
evidence that that's how we naturally
were designed and have evolved to sleep
I in truth I don't think so at least I
don't see good evidence right now
supporting that but remain open to it in
episode one we talked a little bit about
body position during sleep uh and how
different uh degrees of uh incline or
decline might impact uh some of the
features of sleep and I can't help but
ask now as you uh described this basic
pattern for people that were essentially
experimentally restricted to to the bed
um is there something about being
horizontal that makes us
sleepy there is and it's perhaps not for
the reasons that you would think which
is okay I'm just pre-programmed when I
lie down and my head hits the pillow it
turns out that it seems to be
temperature that when your body is
recumbent lying flat
horizontal the distribution of how your
body is able to move blood around the
different regions and decrease your core
body temperature meaning it can push
blood warm blood out of the core of your
body to these surface areas and when you
push it out to the surface areas you
release that heat it's this huge thermal
dissipation that happens when we move
Blood Out Of The Core to the surface you
emit that heat and your core body
temperature plummets when your body
temperature your core body temperature
decreases you have a higher likelihood
of sleepiness in fact it's very
difficult for you to fall asleep if your
core body temperature does not drop and
by lying down the body's what we call
vasoactive ability to distribute that
blood in a way that is permissive for
thermal dissipation of core body
temperature is superior and that's the
reason why we find it easier to fall
asleep lying down than let's say
semi-recumbent or certainly propped all
the way up and it's probably the reason
naturally we evolve just to lie down on
the floor very
interesting maybe now is a good time to
talk
about basic sleep in the context of a
about of sleep at night and the
afternoon nap you've mentioned this
postp parial dip that most people
experience between 1: and 400 p.m. that
many people try and combat with caffeine
we will also talk about Caffe
uh this episode um such an interesting
substance and I think the most commonly
used drug it is a drug after all
worldwide I think more than
90% of adults worldwide consume caffeine
on a daily basis that's correct and I
believe it is after oil it may
be perhaps the second or at least the
third most traded commodity on this
planet and it is what we call a
psychoactive stimulant is a stimulant
and it's probably one of the only
stimulants that we will readily give to
our children and you know not be too
concerned about it we'll get to caffeine
in depth uh a little bit later in this
episode but I can't help but uh just
mention that someone I think it was
Michael Polland said that you know
caffeine is one of the few drugs that
almost everybody takes just to quote
unquote feel normal yeah exactly you
know it's sort of I think sometimes you
know sleep deprivation is is
simply just the absence of of caffeine
and um so it's a very interesting
chemical which I have in truth changed
my mind on and I'm happy to speak about
why I've changed my mind but also some
God rails too well we'll we'll go there
meanwhile I'll take a sip of my uh
Triple Espresso here as we discuss as we
discuss naps are naps good for us should
we nap what if we don't like naps why do
we wake up from naps groggy sometimes
and other times we feel refreshed tell
us about
napping naps are both good and bad
depending on the situation naps can be a
double-edged sword in other words we and
others have done lots of studies on naps
and the benefits are fascinating and St
I'll tell you about one study we did we
had participants assigned to one of two
groups and at midday they all learned a
whole list of new facts so it was a
study about learning in memory and then
one group took a 90-minute sleep
opportunity sort of focused right around
that drop in alertness the other just
remained awake lying on a bed and they
just watched a nature
documentary and then 5 hours later we
had them do another learning session and
so they've woken up after the 90-minute
nap they've got through that sort of
initial lull that we'll discuss what
that is after you wake up everyone's now
back to operating temperature so in
other words I've had you try to cram in
a whole list of facts at midday and then
a whole list of facts new facts again at
5 p.m. and I can ask what is the
learning capacity of your brain at
midday and at 5:00 p.m. and is there any
difference in your learning ability when
you have had a nap in between versus not
and sure enough what happened in the
group that did not nap their learning
capacity gradually declined across the
day the nap group they were able to
sustain their learning and in fact if
anything improve it and the difference
between those two groups at 5:00 p.m.
was about
20% so that's certainly non-trivial in
terms of if you to say you know here's a
new compound that can boost your
learning capacity by 20% would you take
it I suspect it would probably make some
money so that's a demonstration of for
learning in memory we did another study
very much like that in terms of its
design but we looked at your emotional
brain and we were showing people
different types of emotional expressions
and having them rate them and we did
that firstly before an appp and then
after a na versus um that same time in
sort of midday versus 5:00 p.m. and
another group did not nap and sure
enough the group that did not nap
by about 5:00 p.m. they were starting to
rate fearful faces and angry faces as
much more fearful and much more angry
but if you looked at the group that
napped it was different they actually
lessened the response to fear and they
blunted the normal increase in Anger
sensitivity across the day and the nap
seemed to boost how positively you rated
happy faces
so a nap there had the ability to reset
the magnetic north of your emotional
compass and there was a beneficial
almost added Rose tint to your world viw
glasses after You' napped what was also
interesting in those two studies two
different types of sleep were
transacting those benefits in the nap
group that was doing the learning the
learning benefit that they got wasn't
just about them napping and sleeping it
was about them having these sleep
spindles the more of those sleep
spindles that you had the greater the
restoration of your learning capacity
when you wake up for the emotional
recalibration that I described in the
nap that had nothing to do with sleep
spindles or even non-rem sleep it
required REM sleep to produce that
benefit so there are certainly many
benefits and we've look downstairs in
the body blood pressure cardiovascular
measures immune Health they all seem to
benefit so at that point everyone may be
thinking of course this sounds good not
to mention the basics which is your
attention your concentration your focus
and your energy all improve by way of
naps even your decision- making you said
decision making yeah even your
decision-making is improved so your
capacity to make the correct decisional
outcomes based on this weight of
evidence that you're facing that's also
improved so almost all areas of
cognition that we've looked at and many
areas of your emotional and mood Health
we've looked at seem to benefit by way
of a nap at that point you're thinking
so then what's the problem the problem
is that when you nap you release some of
that sleep pressure that's been building
up so in the first episode we spoke
about a chemical called adenosine and
the longer that you're awake the more
adenosine that builds up the more
adenosine that builds up the sleepy you
will feel and after about 16 hours of
being awake you should have lots of
healthy sleepiness of adenosine in your
brain to put you asleep and keep you
asleep and when we sleep we are able to
clear that adenosine from the brain so
we wake up after 7 to 9 hours and if
it's been good quality sleep we're
refreshed because we've cleansed the
brain in part of that
adenosine when you take a
nap like a pressure valve on a steam
cooker you just Rel relase some of that
healthy sleepiness that you've been
building up so the the Dark Side of
napping is if you are struggling with
sleep and you suffer from insomnia the
advice is do not nap during the day
because you're setting yourself up for
an even higher probability of failure at
night why because when you nap you
release some of that good sleepiness
that we need to build up for you as
someone who is struggling with sleep to
give you the greatest chance of awai of
sleepiness on your
shoulders so if you are not struggling
with sleep and you can nap regularly I
would say naps are just fine and we can
unpack what is an optimal nap and the
protocol for what napping should
be I would say that's great the only
caveat is make sure that you're not
napping too late into the day and this
is one of the components of the protocol
of how to nap because napping late in
the day is too close to sleep and you
can think of it almost like snacking
before your main meal a nap late in the
day just takes the appetite edge off
your sleepiness so that when it comes
time for sleep you're not as hungry
anymore so just keep that in mind but we
can unpack perhaps the optimal way to
nap if you are going to nap and exactly
the dos and the don'ts of that if that
sounds of somewhat interest yeah that is
uh of immen interest to me and I know
many other people I'm a huge believer in
naps I've always enjoyed um short naps
of about 10 to 30 minutes unless I'm
somehow sleep deprived in which case I
will sleep for an hour or even a little
bit more but I make sure I set an alarm
U really based on advice that you gave
me which was to um first of all decide
whether or not a nap is beneficial for
for for me or for whoever is considering
that um but then to make sure that
however long that nap is zero to 90
minutes that it not be longer than 90
minutes because the real goal is to not
disrupt nighttime sleep that's right
which is essentially just a a more
long-winded way of saying what you just
said so how does one determine the
optimal duration of nap um and in
particular to avoid the problem of
disrupting nighttime sleep by napping
but also this uh rather common
phenomenon of waking up and feeling kind
of groggy or even I'm kind of grumpy the
post-nap face uh or we should call the
post-nap expression
right right the P NE what's your P are
do you wake up um in the and for morning
too some people wake up and they're like
that that face and then there's the like
good morning you know and I think people
that wake up with the good morning are
particularly delightful unless you're of
the post Snap expression that is kind of
the the crumpled face and then you just
you don't want to be around those people
right no absolutely
um yeah and this probably relates to
spirit animals and things like that some
people wake up like a like a cheerful
chipmunk and other people seem to wake
up like my Bulldog Costello where it's
you know um jowls still in contact with
the floor yeah so um P I'm trying to
hold it together and not Absol just fall
apart it's brilliant please trademarket
so firstly to your question how to
optimally nap the word optimal is
interesting because
when you people say how long should I
nap what's the optimal nap duration the
question I have back to them is what are
you trying to optimize because once I
understand what you're trying to
optimize I can give you a better
prescription non-medical I'm talking
about here the a better sort of you know
protocol piece of advice for how to nap
I mentioned the study about emotional
faces in part for a specific reason cuz
I told you there the benefit came by way
not of non REM sleep but REM sleep and
in our first episode we said that when
you go through these on average 90minut
Cycles you get most of your non-rem
sleep first and then you'll have this
bout of REM sleep at the end and it
always seems to go that way when you are
a healthy normal person you go into
non-rem sleep and then you go into REM
sleep it's very rare that you ever go
directly into REM sleep there are only
two reasons when that seems to happen
the first is a clinical condition called
noopsy where you can have sleep onset
REM sleep and very rare the second is if
you are horrifically deprived of REM
sleep night after night after night and
I let you sleep then at that point REM
sleep the pressure for REM sleep has
been built to to the point of being
almost just insatiable and your brain
goes straight into REM sleep but with
those two things aside you go into
non-rem sleep first so I brought up the
emotional study of resetting your sort
of mood uh compass
because to get that REM sleep you had to
nap for a longer period of time because
you had to get through the non-rem sleep
first before you get the REM sleep but
let's come back to then assuming optimal
is for most people when they speak about
naps I just want the quick reboot I want
my alertness and concentration which are
failing because I'm staring at the
screen or I just can't concentrate on
the work that I'm doing I want my
alertness and my concentration to be
improved proved I want that sort of
slight boost in brain energy where I
know I can sustain myself for now a
longer period of time and I've got the
motivation which is really in some ways
how I like to think about energy as well
I've got the motivation the drive to
keep going which is just starting to
fail me to get those basic things which
is what most people nap for aim for 20
minute nap why 20 minutes if I thin
slice the nap duration and and those
Studies have been done where we look at
essentially what's called a dose
response curve I give you 5 minutes of a
nap 10 minutes of a nap 15 minutes 20
minutes 30 minutes 45 minutes 90
minutes after 5 or 10 minutes you don't
really get very much you will wake up
and you'll have some degree of improved
alertness and your basic reaction time
may be a little bit quicker but that
Fades very quickly and you don't sustain
that
benefit once you get past about 15 to 17
minutes now things start to look
different you get these nice benefits
for concentrational alertness and
motivation and those things sustain so
once you wake up out of that probably
really I would say 20 minute nap at that
point you've got some good wind in your
concentration and energy sales for the
brain and that will sustain you
throughout the rest of the afternoon and
into the
evening the benefit of the 20-minute nap
is that you don't get the
PNE trademark Andrew hubman you don't
get that almost sleep hangover so some
people will say it's strange I nap maybe
I'll nap 45 minutes 50 minutes and I
wake up and to be honest Matt I almost
feel worse after the nap than I did
before and I don't understand it it's
something called Sleep inertia
and an extreme version of this is in the
first two hours of your night of sleep
you get a phone call or an alarm goes
off and you wake up and you are just
kind of lost in the ocean you're looking
around at your surroundings you're just
in this groggy State you're half awake
half asleep and you can respond and you
can do things but boy does it feel
miserable and it's almost as though
you're going from the ground floor right
up to the penthouse suite but you get
stuck somewhere in between kind of you
know floor 13 and it's this rough
state if you go out into sleep light
stage one nonrem then stage two nonr and
just before you get into the very
deepest stages of non Ram 3 and four
that starts to happen around 30 to 40
minutes for most people but by cutting
your nap off at 20 minutes you still get
these nice benefits from a good chunk of
healthy non-rem sleep but you're not
going so far into the cycle so deep into
your nonr that when you wake up after 20
minutes you're not in that what we call
Sleep inertia phase that sleep
grogginess that sleep hangover phase so
it's a nice benefit that you get all of
these improvements in your brain but you
wake up and very quickly you're back up
to operating temperature and you don't
suffer that inertia now that's not to
say that when you sleep or you nap
longer
you don't start to get more benefits you
do and those benefits are both greater
in their magnitude and sustain for a
longer period of time they do it's just
that you have to understand the tradeoff
that you will suffer which is I will get
more bang for my book and I will get
more benefits but I will in the first
sort of hour or so have to understand
that at that point I may even be
functioning worse than than that which I
did before I even started napping but if
you're patient and you go through it the
rewards on the other side are
significantly better still so that's the
first piece of advice and when it comes
to how to nap I would say the dose and
the timing make the poison and poison is
hyperbole in here it's simply just the
poison being how much sleep and nurs
you're going to suffer so aim for about
20 minutes that's the do the timing
comes back to that which we described
before do not nap too late into the day
so what's the rule of thumb here for a
protocol on average for the average
adult I would say don't nap after about
300 p.m. 20 minute naps sometime between
300 p.m. and if you're struggling with
sleep don't do this at all if you're not
and you're able to get to sleep fine
this seems to be a good ingredient for
the basic return on your investment
again if you tell me what's the optimal
nap duration we need to have a
conversation to understand what is it
that you're going after here what are
the benefits and then I can sort of you
know create a finger Buffet Kaleidoscope
match to what you need and we can think
about the nap duration as a consequence
thank you that's very informative um I
have a colleague at Stanford who's a
Howard Hughes investigator which for
those that don't know is a a rather
elite club of uh academic research they
have to essentially try out for it they
can every 5 years they go up for Renewal
it's it's a lot of money which makes
gives them a greater capacity to uh take
on greater risk uh work higher risk work
um and he's also a member of the
National Academy and he was one of these
people that graduated high school at 15
years of age one of these phenoms and he
is so religious about his napping such
that when he travels to give seminars at
other schools he insists that they
schedule a nap time for him after lunch
and in his office um you know at between
12:30 and and 1: p.m. he's napping
everyone knows this and um and I mention
this because I think that um oftentimes
people think of the Nappers as the lazy
ones but um his output is um near
superhuman and he attributes U much of
that output uh to the nap not just the
post-nap work that he's able to perform
but his ability to uh just kind of
manage so many ideas he has enormous
laboratory and that's just one example I
think there are examples from sport of
um sprinters taking naps on the you know
on the side of the the track field I
mean so it seems that a capacity to nap
is also something worth considering
because I think many people listening to
this are thinking well I can't nap
should I nap you know um and can one
teach themselves to nap so that's the
question um if one would want to explore
napping and um is that something that
one should even consider doing if you
don't have a propensity to nap should
you avoid it if you want to try naps how
could one teach oneself to nap you just
mentioned earlier uh lying down uh
relates to body temperature body
temperature uh relates to sleepiness and
then as a third question I promise I'll
repeat these if we need to uh as a third
question I'd like to have a little bit
of a discussion about some of the pseudo
naap states that um I certainly am
intrigued by you know for instance just
lying down and I'm doing a progressive
bodily relaxation things like Yoga Nidra
uh non-sleep deep rest which is an
acronym ioin simply to to um make it
clear what I was talking about but it's
very similar to Yoga Nidra um things of
that sort in other words but simply
should everyone think about having an
early to mid-afternoon
protocol to reset their cognition and
their body we call it a nap but does it
have to be a nap and if we're not good
Nappers should we try and if so how
should we go about it yeah so TI your
three questions firstly if you're not a
natural Napper should you start doing it
um if you want to start doing it how
should you do it and then the third is
is there some kind of you know
substitute for a like kind which would
be these Li these I I'd love the
phraseology that you use these Lial
states do they mimic that are they
different to that how should we think
about those the first thing I would say
to point number one if you are not a
natural Napper don't necessarily Force
yourself to be as long as you're getting
the sleep that you feel you need at
night and you feel refreshed and
restored during the day and you don't
have that sort of postrenal drop to the
point of thinking I almost need to nap
during the day there is no pressure
based on anything I've been telling you
for you to start napping nor should
there be any reason that you do start
napping but let's say that you want to
try what would be the right protocol to
improve and increase the likelihood
the best way you can do this is to mimic
nighttime as best you can so wherever
you are if you can shut off the
lights make sure that you can block out
you know curtains blinds if you can't do
that fully and many people won't be able
to develop an IM mask procedure um so
put an IM mask on make sure you block
out noise earplugs you can use a sound
machine if you want and we can speak
about sort of sound machines and whether
or not they're good or bad on sleep and
then you can lie down make sure that you
try to take your shoes off and get under
some kind of a blanket because we're so
Contex cued by having something wrapped
around us called a blanket or a duvet
that to do it without that if you are
not a natural Napper can help you again
that some people will say I can just
kick my feet up on my desk sit back in
my reclining chair in the office and I
can fall asleep that's great but if
you're not a natural person I'm just
trying to tell you things that increase
the probability of that and then set the
alarm I like your idea of making sure
that if you do fall asleep you don't
accidentally go too long and then just
feel miserable so mimic the conditions
that you're trying to get that you would
normally get at night that will increase
the probability mask out noise mask out
light kick your shoes off have some kind
of a blanket wrapping around you that's
probably the best and then time it based
on this sort of post pral drop you will
know yourself everyone has fallen prey
to it you know W it's usually around
about 3 4 p.m. that I do start to feel
this decline or it's around 1 p.m. try
to match it in accordance with that so
those are the first I think two
questions should you not necessarily if
you would like to and I'm not normally
doing it how can you do it the final
point I think is fascinating which is
these alternate states
of conscious brain activity the most
obvious is when we're awake and when
we're asleep those are the two most
dramatic changes in Consciousness that
we experience on a daily basis short of
anesthesia I've become like you very
fascinated by these sort of both
meditative States or these linal states
I think at some point you and I should
collaborate and we should do some work
and really unpack this but the reason I
find this interesting is because I'm
going to guess you are having sleep
likee States but you are not fully
asleep how would I Define a sleep-like
state what we've learned is that your
brain the way it sleeps isn't on mass
it's not as though your entire brain
sleeps different territories of your
brain can sleep in different
ways and what we've also known and
there's some argument even individual
brain cells seem to have a period where
they go into sleep and these individual
neurons will start to show what look
like these beautiful big powerful deep
slow waves in terms of their firing rate
at least in terms of those neurons
firing away I bring this up because if
that means that your brain can have
local sleep rather than Global sleep if
you are in global sleep you're out like
a light you are a sleep but perhaps
these Lial States the reason that they
give these benefits is because you are
still awake not Global sleep so if
you're in global sleep you're asleep but
you're awake so you're not in global
sleep but you may be having local sleep
now using special um setups in my
laboratory we can apply tens maybe
hundreds of electrodes all over your
head and we can map the the sort of the
the different places where your brain is
having sleep in much higher resolution
so rather than a you know 480 DPI movie
on YouTube I'm now in 4K resolution I
can really dismantle what's going on um
analytically in your brain I'm going to
guess that when you're going into these
states and you report coming out of
those states and I ask you on a scale of
1 to 10 how would you rate that as an
experience based on your common
experience the greater the intensity of
the lional benefit and state that you
experienced I'm going to predict is
directly related to the extent of this
this local deep non-rem slow wave sleep
that's happening you're still awake but
some parts of your brain for maybe
seconds of time or maybe even tens of
seconds of time I'm going to bed will be
oscillating in what look like slow wave
sleep deep sleep States and if all I
would be able to look at is that one
part of your brain and that small
cluster of electrodes and someone said
to me is this person awake or asleep I
would say oh they're asleep they're in
deep sleep but then if you slowly reveal
and back out and show me the rest of the
brain and what it's doing I would say oh
my goodness no this person must be awake
but that local territory that District
up there in their brain they were having
slow wave
sleep I think that's what we could find
and that may predict some of the
benefits that you get some of the
productivity energy benefits by the way
I should note that with all of this nap
racket NASA figured this out back in the
1980s they were looking at ways to
optimize their astronauts because when
you are up in orbit depending on what
orbit you're in you are rotating around
the planet maybe 10 and 20 times per 24
hours so you're seeing 10 to you know 20
sunsets and sunrises so your sleep is a
total mess and you can safety check
almost everything in terms of Technology
but the one weak Link in a space mission
is this thing called the human being
that's where errors typically happen so
how do you drisk a human error up in
space because if you make an error up
there I mean on the ground not great up
there kind of
catastrophic you can try to optimize
their ability to sleep and their ability
to maintain Focus concentration
alertness and productivity and what they
found was that these naps produced
almost a 20% boost in short naaps 20%
boost in their alertness and almost a
50% boost in their task productivity and
it was so powerful that it translated to
the terrestrial um employees of NASA on
the ground and it became what was known
as the NASA nap
culture and from there on we had what we
called power naaps Power naaps by the
way why are they called power naaps and
you think well just because it Powers me
up it's a good idea but it's wrong it
has a very specific story a fascinating
one two legends in my field David dingis
uh and Mark Rose kind they were looking
at how to instigate
risk mitigation not in astronauts but in
pilots who are doing long haul
flights because the most dangerous
aspect of a long haul flight is when it
is coming down to land and that's when
they can sometimes have these things
called a catastrophic hole loss which is
a euphemistic phrase for a terrible
plane crash and they were trying to say
how could you use nap
strategically to drisk that and improve
their
alertness and they asked a very
interesting question if they can nap for
only a certain period of time because
they have to be at work on the plane at
the for the rest of it when should you
place that nap should you do it at the
start of the long call flight in the
middle or towards the end and most
people would bet like they I think did
it's best to place it at the end when
you're really starting to struggle get
that boost and then you wake up you're
not in sleep in OA cuz it's been brief
and then you're energized for landing
they didn't find that they found that
the most optimal time to nap was early
on in that long haul flight and it
sustained them throughout the rest of
the flight now they took their findings
to the FAA who were funding the work um
and the Federal Aviation Authority here
in the United States and they said we've
got some great findings and we think we
should implement this and we would like
to use a term to help Pilots understand
this and it's called prophylactic
napping and of course there were many
Chuckles throughout the room perhaps
inappropriate and they just said look
you've got to understand our Pilots the
you know kind of alpha male guys and if
you're starting to say you need to
prophylactically NAB it's not going to
be adopted that's a nogo so they looked
around the room because it's an alpha
male culture it's a mostly masculine
culture at that time they said what
could we and there's a lot of beard
stroking and they said I've got it power
naaps it's got to be about power and so
that is where if you've ever wondered
where the term power naaps come from
it's not because it reboosts your power
which it does and boost it back up it's
because there was Chuckles at the time
prophylactic napping I'd like to take a
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huberman the naming of things fascinates
me especially in um the uh landscape of
health and well-being um also um and
that's one reason why um having become a
real fan and practitioner of Yoga Nidra
which I think translates to yoga sleep
which is this process of lying down for
a period of 30 to 60 Minutes Progressive
relaxation this is these are scripts
that are readily available as this is a
a uh age-old practice um in in India um
that is meant to restore mental and
physical Vig Vigor by placing one into
one of these Lial States the um and I
have great respect for the uh ner
tradition um but um sometimes the names
are a separator so people who hear Yoga
Nidra and they think oh it must be yoga
movement and that's of course not true
or they think um that there must be some
mystical component to it which is not
necessarily true sometimes they include
intentions and things like that but
often not so that's why I coin this um
uh phrase non-sleep deep rest which is
essentially maintains the
critical components of Yoga Nidra um but
doesn't include intentions and um has
these shorter uh 10 or 20 minute um
protocols so it'd be um great fun and um
I think very interesting for us to do
that project to explore what are the
brains uh activation States or
deactivation States as the case may be
in these um non-traditional or Lial
State uh practices now um along the
lines of power napping specifically and
the naming of power napping I think it's
more than than just a a um anecdote
because I think it is very important for
people to understand that um that these
protocols these tools that NASA and that
Laboratories have have developed um
often times are are for other purposes
but they translate to a kind of broader
significance and what I'm hearing and
what I'm starting to integrate as we
have today's conversation is that it
seems that there is pretty good reason
to ex at least explore basic sleep right
that that for the non-nappers to to
really think about whether or not they
would like to explore napping as you
mentioned they don't have to and then
for people who are already um napping to
really think about the placement of that
nap uh within the day and the duration
of that nap what you told us a few
moments ago suggests that I should be
doing or anyone that's doing naps or
entering these Lial States like nsdr
might want to shift them a little bit
earlier than uh the period in which they
first become sleepy to take that nap is
that right I mean like so for instance
should I do as my colleague and you know
finish lunch and and lie down for 10 15
minutes um rather than wait until 2 or 3
p.m. is that is that something that that
could make a meaningful difference I
think it could and I think it really
again depends on how much of a struggle
sleep becomes in the evening for you if
it is becoming the later that you nap if
your sleep becomes either a more
difficult to initiate in the evening or
maybe you don't have any problems
falling asleep but for some reason when
I look back I'm now starting to wake up
more throughout the night that in part
again it's not just that if you nap late
in the day you struggle to fall asleep
you may not the other consequence that
can happen which is non-mutually
exclusive is that you then stay in not
as deep as sleep and your sleep is more
some more fragile in that sense so the
probability that you will wake up
because because you had the nap so late
in the day is higher in the middle of
the night and then when you wake up like
many of us do and you go to the restroom
or It's Perfectly Natural but the speed
with which you can then fall back asleep
is compromised why because you've
jettisoned some of that sleepiness by
way of the nap and there isn't as much
to take you back down into sleep after
you've woken up so I would just say that
if you are seeing that pattern that the
later napping that you're doing if
you're doing that and again there's no
reason that you need to nap only if you
choose to nap if that's the case then
consider not necessarily obviating the
nap that may not be required just bring
it back earlier take it after lunch see
how things work out do the experiment
and when you do the experiment make sure
that you do what I would describe as the
onof on experiment which is where you're
napping as you normally do and you've
noticed perhaps some problems with your
sleep then do so that's sort of the the
well it's sort of the on off on phase so
then change your nap protocol and move
it earlier so now you've Switched Off
Your Standard protocol and you've moved
on to something different so you're on
your standard protocol and then you come
off it and when you come off it meaning
you go to an earlier nap and you say
gosh things do seem to be better maybe
he he had something there and it does
seem to
improve good but I don't trust that
because maybe it's just a placebo effect
that you you know hear some dulit
British tones and you get convinced that
maybe that would work and you've now
instead after about two weeks of doing
that and things have improved go back to
your original schedule go back on to
your original protocol I'm not as
interested about the fact that things
got better when we changed it I'm
interested in the question do things get
worse when we stop it and so when we
stop the intervention if things got
worse again now I'm I'm believing it a
lot more so just as a tip if you are a
self- tinkerer and you don't have to do
that but if you're idiotic like me and a
scientist and you want to do it with
this city riger that's the way I would
suggest doing it I don't think it's
idiotic at all I think it's systematic
and what you just described is uh both a
negative control and a positive control
experiment so you're you are a scientist
through and
through are there any individuals that
should absolutely avoid napping you know
I'm heard lore of you know um elderly
folks um folks with certain conditions
um you know can't imagine um which but
um I'm sure you'll tell us that for whom
napping is harmful to their health it's
a very I think interesting question
because the strongest evidence comes
back to that which we we've mentioned
before which is insomnia and really the
recommendation there is just avoid naps
it's and what's problematic about
insomnia when you are having such tough
times with sleep at night and you are
just dragging through the day it is
miserable and I am you know I I'm very
protective of my sleep um for the most
part I
sleep pretty well but I've I'm I'm not
immune to the vagaries of sleep I've had
two bouts of insomnia throughout my life
both have been what we call reactive
insomnia reactive to an event or
something happening and I know how just
desperate and hungry you are for sleep
and if it's happening week after week
month after month I'll just do anything
to get sleep when I can and the
Temptation therefore to nap when you are
suffering from insomnia is that much
higher and therefore the advice is that
much harder to adopt but trust me that
is one of the components that we have in
the psychological treatment bucket that
we use for insomnia which is called
cognitive behavioral therapy for
insomnia or cbti for short and you can
just look it up or um on my own podcast
I done a six-part series on on uh
insomnia so I would say try to back away
in that circumstance but you brought up
a another example which is in aging
there I think the evidence is a little
less causal so you have to be more
cautious about recommending the absence
as I was with insomnia of abstaining
from naps but the data has now become
quite strong that when you get past
about 65 years old and you look at
napping behavior in large
epidemiological studies and you say is
there a positive benefit in aging for
napping or is there no benefit at all
and they looked at that because they
thought well that perhaps based on the
work in healthy adults that I've
described that would be good for older
adults not only did they find that it
wasn't good they found that it was
deleterious that napping in older adults
was predictive of worse Health outcomes
and it also seemed to predict a higher
likelihood of early
mortality so at this point we're
thinking well how does that fit with
everything you've been telling us it
comes back to this notion of bad sleep
at night it's probably not necessarily
that napping during the day is bad for
older
adults it's that the Naps reflect a
problem with the night of sleep for
older adults and as we get older
something I didn't mention during
development was that yes we get this
sort of State Lael ratio of 4 to1 of one
part REM sleep four parts non-rem in our
7 to9 hours and I described these
changes in rem early in development I
didn't mention two things about non-rem
slow wave activity first as we go into
our teenage years and we shift our sort
of timing of sleep where we want to go
to bed later and wake up later that's
biologically determined it's not
teenagers fault something happens with
their deep sleep however their deep
sleep starts to do a
different or different action to the
brain that REM sleep was doing as an
infant I said that during infancy we
have huge amounts of REM sleep and were
growing sinapsis syap Genesis and we
wiring up all of those new territories
all of these new neighborhoods with
fiberoptic cable but let's say that
you've now run the experiment across
many years through until teenagehood of
those neighborhoods and you've been
measuring the bandwidth consumption of
each individual house and you've started
to realize well I wanted to create a big
spread across the brain and then I'm
just going to let experience over the
next years time tell me which parts of
the brain seem to enjoy that high
bandwidth and which parts don't seem to
use it very much and as we go through
into our teenage years we go through
something called synaptic pruning where
the brain actually calls and takes away
copses from certain parts of the brain
it seems to be that this change in slow
wave sleep that happens around these
adolescent years is performing the act
of final cortical
maturation that it's downscaling the
synapses and fine-tuning the brain so
you've got this beautiful efficiency and
now you've throttled back some of the
bandwidth from some of those
neighborhoods because they just don't
use it very much and you can move it
over into the territories that are
demanding more bandwidth and net net the
brain is downscaled but it's improved
its efficiency in the sense that those
regions that need it and are working
hard based on what we think this
organism has been doing over the past
you know 13 years that's where we need
to now place our bets but as we get
through into our older years and this
will come back to this issue of napping
don't
worry stick with me here folks um the
reason is that as we're getting older
our sleep de
deines but it's not just all sleep
declines deep sleep declines most
dramatically and we all think of aging
from brain perspective as cognitive
decline that our learning and memory
abilities begin to fade and Decline and
they do but I would argue that a
physiological signature of Aging is that
your sleep gets worse and particularly
your deep sleep what's perhaps
concerning for people listening to this
right now is that that decline in deep
Sleep doesn't start happening in your
60s or your 50s or even your 40s we can
start to pick up that great sleep
decline beginning in your mid to late
30s and then it just decreases and by
age 50 you are down to about 50% of the
deep non-rem sleep that you were having
when you were 17 or 18 by age 65 and
over or certainly by age 75 you are down
to about just 5% of the deep sleep that
you had when you were 17 or 18 which is
a stunning
decline what that means comes back to
the first episode we spoke about the
four macros of good sleep quantity
quality timing and regularity one of the
measures of quality that I described to
you was this electrical quality of deep
sleep the other measure of quality sleep
I spoke about was how consolid ated and
consistent your sleep is versus how
fragmented your sleep is the measure of
Sleep Quality is markedly compromised as
we get older we're waking up many more
times our sleep is much more fragmented
and therefore our sleep efficiency is
worse and we've got this huge decline in
our deep non-rm sleep so no wonder then
when you are awake during the day as an
older adult Your Sleep Quality is so
compr promised at that stage you perhaps
try to compensate by way of napping but
that compromised quality of sleep that
you're having at night is probably the
reason that you start to get sick more
that you have a higher probability of
illness and disease and why also you
probably have a higher risk of premature
mortality so in other words it's the bad
quality of sleep at night that leads to
this behavior that we call daytime
napping in older adults
that seems to indirectly suggest oh my
goodness it's daytime napping that's bad
and that causes these problems when in
fact it's that daytime napping is a
proxy for the bad sleep that's happening
at night and it's really the bad sleep
that's happening at night that is more
directly related to the health and
mortality concerns in older adults so
that's why I think right now as a field
I'm still open to evidence that napping
for some reason that we just do not
understand right now is problematic and
does causally predict worse health and a
shorter lifespan in older adults I think
the best evidence that we have right now
is that it's actually the bad quality of
sleep at night and thus we should not be
necessarily jumping to recommendations
that all older adults should stop
napping I think we need more evidence
and I'm open to both sides of that let's
talk about caffeine uh I've heard the
ter term is it
napino yeah I I I think it um refers to
a practice of drinking some caffeine
then laying down for a nap and then
supposedly waking up um feeling more
refreshed my understanding and you'll
tell us more of course is that caffeine
um is effectively uh an adenosine
antagonist although it's a competitive
Agonist and you'll explain I'm sure um
and napping as you mentioned before uh
removes some of the Sleep pressure AKA
uh wipes away some of that uh adenosine
that's accumulated um both of which
sound great but as you mentioned earlier
there's a warning there as well uh the
warning label on uh both those things
should be that having sufficient
adenosine built up in your brain is one
of the ways in which you feel sleepy at
night and fall asleep and stay asleep
yeah so what's the story with caffeine
how does it work uh to make us feel more
alert and
um what is the rationale for the
nappuccino the nappuccino also known as
the caffeine nap caffeine is a very
interesting compound in relationship to
sleep and wake obviously everyone knows
that caffeine can help you stay awake
it's no coincidence that those two words
that you've used about these chemical
compounds caffeine and adenosine sound
the same it's because the re receptor
that or the receptor systems that
caffeine Targets in your brain are the
adenosine
receptors and you think well Matt was
telling me that the more adenosine that
builds up in other words the more
adenosine that's latching onto those
adenosine receptors in your brain the
sleepier that you feel and I'm telling
you that caffeine works on those same
receptors that doesn't make sense
caffeine if it's working on those same
receptors should increase your
sleepiness it doesn't because it when it
binds onto those adenosine receptors
those welcome sites in the brain it
simply blocks them it doesn't deactivate
them nor does it activate them it simply
blocks them so think about it almost a
little bit like um a room that's full of
chairs and at some point these adenosine
which is one collection of people with
the name badges of adenosine they would
normally like to come in and start
sitting down on those seats which are
the adenosine receptors and as they sit
down on those seats you're building up
this signal of sleepiness well caffeine
which is another group of people with
caffeine badges they race into the room
and they start to hijack the seats and
they start to sit down on them and all
of a sudden adenosine can't find any
seats to sit on so your brain is still
flooding that room with adenosine so the
adenosine is still building up but the
reason that you don't feel sleepy
anymore when you've had a shot of
caffeine is because caffeine is raced in
it's latched onto the
receptors and it has essentially hit the
mute button on your
sleepiness so now your brain was
thinking gosh I've been awake for about
13 or 14 hours I'm starting to feel it
I'm just going to take a quick espresso
shot and you get that you don't think
well hang on a second you know 20 30
minutes later I don't feel as tied
anymore why it's not because caffeine
came in and removed the adenosine it
didn't caffeine has come in blocked the
sights but the the adenosine is still
building
up and then at some point the caffeine
wors off and therefore not only do you
go back to the same level of Denine of
adenosine that you did 2 hours ago it's
that plus the additional 2 hours of
adenosine that has been building up and
what you experience is something called
a caffeine crash and now you need even
more caffeine not just to get you back
to where you were but to recover the
crash that you've had and go
further caffeine in relationship to the
caffeine nap though the
napino is relevant because of its
timing caffeine has an instigating
action of around uh 12 14 to 17 minutes
so when you come through in the morning
and you grab your first cup of coffee
and within the first four or five
minutes you you say I just I just feel
better I've just had a couple of sips
I've had half a cup of coffee and I
already feel better I just needed that
if it's within the first five minutes
that you're experiencing that it's got
nothing to do with the caffeine because
the peak plasma concentration of your
caffeine is not going to arrive with you
until about you know 12 to 17 minutes so
why do you feel better some of it is
Placebo because you're smelling the
coffee and you associate it with the L
it's really not that though or or um
when you say Placebo I also wonder
whether or not it's possibly a a
conditioned effect you know like a
pavlovian thing because the smell of the
coffee the taste of the coffee the the
hum of the machine the walking into the
cafe
to to um and ordering it from the
Barista also creates an anticipatory
arousal like here the the alertness is
coming and in that anticipation there's
its own form of alertness I think that's
that's certainly a big component of it
the other component however if you look
at the data is that it's got nothing to
do with the caffeine in that moment it's
the temperature that most people take
their caffeine warm either it's tea or
it's coffee or it's perhaps something
else that Andrew hubman would drink but
many people yamate since since I was 5
years old I don't I don't know if I
should have been drinking uh caffein
yerbamate so young maybe even four years
old there's a photo of me on my
grandfather's lap drinking out of the
mate gourd half my family is Argentine
and um so I was caffeinated from a young
age this brain developed in a
caffeinated millu this explains so much
about what I've known of you over these
no I'm kidding you um so um but we need
to speak later no so what's interesting
about that is it's the
temperature and I told you in the first
episode that we need to cool down
to stay asleep but we need to initially
warm up to fall asleep because warming
up at that moment I was telling you is
warming up at the periphery a warm up to
cool down to fall asleep so you need to
warm up to cool down to fall asleep then
you need to stay cool to stay asleep and
then you need to warm up to wake up the
warming up to cool down to fall asleep
is not warming up in the middle deep
core of your body it's about warming up
the hands and the feet and the head to
dissipate the heat hence warm up the
outer surfaces to cool down the inner
core to fall asleep but then I told you
you have to warm up to wake up and when
we take a hot drink in the morning
usually caffeinated the change in your
core body temperature can happen with
within a handful of minutes so the
initial benefit that you get from the
hot cup of coffee in the morning or hot
tea is from the temperature rise and
then you get this beautiful second kick
from the caffeine itself and that
caffeine can then sustain for a longer
period of
time so we mentioned this problem with
napping that even at 25 or 30 minutes of
a nap you wake up with that kind of
grogginess that sleep
inertia and what however if I could give
you the benefits of a nap and have you
come out of the nap with zero sleep
inertia and that's what some folks
started to cleverly think
about what if I could look at the timing
of the optimal nap maybe 20 minutes and
think about the timing of when Peak
plasma concentration of caffeine emerges
and I told you really starts to kick
into gear around 17 minutes and it's in
full swing by 20 what if I was creative
I'm going to withhold from saying
idiotic enough but creative enough to
get into bed just before I turn the
light out for my nap in the afternoon I
Swig a quick
espresso light goes
off I close my eyes eye mask earplugs
and I'm going to drift off fine because
the the caffeine is not going to kick in
and for another 17 20 minutes perhaps at
its full threshold so now you you fall
in to sleep and you're going down into
sleep and if you perhaps don't make it
too large in terms of its serving the
temperature change is not going to
affect you in a negative way and then
just as your alarm clock is about to go
off after 20 minutes you're on the
beautiful ascending swing of upward
plasma concentration of caffeine and you
get ejected out the other side with both
the benefits of the nap together with
the benefits of the caffeine so you get
your cake and you can eat it too you get
the nap absent the Sleep inertia and
hence this created what we call the
caffeine nap I love it the nappuccino
the the nappuccino um maybe I'll give it
a try uh this is the first time I've
ever heard the um the rationale and the
the the fine structure of the nappuccino
but it makes sense um uh at a logical
and mechanistic level I have to ask is
there anything besides caffeine and
sleep that can clear
adenosine you know can exercise clear
adenosine can uh cold shower clear
adenosine I mean and I understand that
there are a bunch of competing
mechanisms in the body like presumably a
spike in norepinephrine or adrenaline or
both is going to impact the adenosine
system I I once heard a great quote um
from a former uh
member of the National Academy of
Sciences a brilliant guy he said you
know a a drug is a substance that when
injected into an animal or a human
produces a scientific publication
meaning meaning it is it is rare to find
a paper that doesn't see some effect of
some drug especially on sleep I'm told
as I recall if you put aspirin REM sleep
into PubMed you're going to see some
effect on REM sleep people take aspir
pretty much any substance that one takes
is going to to alter um some feature of
sleep or of wakeful States if one is
looking with a fine enough uh instrument
or is that an overstatement no I don't
think it is an overstatement and it
comes back to the first episode where we
described the complexity this incredible
beautiful physiological ballet certainly
one of the recommendations when people
say I get this afternoon this post
prandy will drop in my alertness what
can I do I say you could nap but another
way is just get outside and walk around
be physically active some of that has to
do with the fact that you'll probably
get some daylight and daylight can be a
stimulator of alertness as long you've
told us and educated us on we also know
that physical activity by itself can
increase the amount of endorphins and
dorphin and those are wake promoting but
none of those are really necessarily
going to be altering adenosine they're
simply overriding the adenosine that is
still building up it really does seem to
be for the most part at least as all
that I know it's only sleep and
particularly non-rem sleep that has the
capacity to or give the brain the chance
to remove that adenosine now what could
be interesting I think is two
circumstances one is where your brain
becomes less metabolically active for
another reason and I told you that it's
not joring it's not as though during
deep non-rm sleep that there is some
special pulsing cleansing mechanism for
adenosine there is a cleansing system
called the glymphatic system which
removes the toxic metabolic byproducts
of the waking day wakefulness in some
ways is biochemically low-level brain
damage and sleep is sanitary salvation
in that regard knew um but which is
again it's humoristic and it's it's it's
going too far but it makes a point the
idea here however is that it's not that
there is a special system that is
removing the adenosine during deep nonm
sleep it's just that your brain is less
metabolically active and therefore it's
not producing as much adenosine so the
natural mechanisms that are always
occurring in the background to be
clearing adenosine and degrading it
simply get the chance to do that just as
effectively as they have but you're no
longer working against the opposite tide
that is growing the adenosine now the
adenosine increase has dissipated
because you're no long longer
metabolically active during deep sleep
and you get the chance to cleanse it all
of which is to say therefore that and I
think that would mimic that such as for
example anesthesia my guess is that you
probably do jettison some sleep pressure
when you are in
anesthesia I also think that these Lial
States non sleep deep rest could be a
fascinating territory there because at
that point I'm going to guess and we'll
be able to see with the e G and we may
also be able to do some Imaging
depending on how we you and I design the
study to look at what changes in the
brain in terms of its activation State
my guess is that if it does put you into
something like slow wave activity
patterns that means that those
territories of the brain are
metabolically less active and that
allows the brain to dissipate the
adenosine so to your point I don't think
things like necessarily exercise or
light change adenosine level
they do give a nice alertness benefit
for other reasons but is there an
alternative way of dissipating adenosine
yes I think anything that mimics a non
or a less metabolically active brain
could produce these beautiful adenosine
benefits thank you for that this brings
me to a question about the period
immediately after waking from the
nightly bout of sleep um I've been uh
touting the benefits of delaying one's
caffeine intake by 90 to 120 minutes
after waking there's a little bit of a
misconception out there I think people
um ran with the ball uh assuming that I
was mandating this or think or
suggesting that everyone should do this
and that's simply not the case uh I
actually wake up and I'll hydrate and
drink caffeine very close to waking if
I'm going to exercise soon after yeah um
which I often do um but I've experienced
and I know others um have experienced if
they are not going to exercise
immediately or they don't need caffeine
to exercise for whatever reason I've
heard these people exist I'm no such M
mutant um that delaying their caffeine
intake by 90 to 120 Minutes in some
cases can offset the afternoon crash now
I want to be clear some of that may be
offsetting the afternoon consumption of
more caffeine because by delaying your
caffeine intake in the morning then
perhaps there's less of an incentive or
requirement to drink caffeine in the
afternoon and all of which dominoes to
as we'll talk about more in the series
to better sleep at night because you
you're not ingesting caffeine close to
bedtime but at risk of taking a massive
tangent here's what I'd like to know
based on what you just told
us if
indeed
sleep and
lower metabolic activity in certain
brain regions can help reduce adenosine
levels in the
brain one could imagine that upon
waking it is either a step function from
okay you know let's say at um 5:45 a.m.
somebody is asleep and adenosine is
still being cleared away because they're
asleep and then they wake up boom does
adenosine clearance immediately stop
well for people who have that um
crumpled face uh grogginess um and they
wake up at 5:45 maybe even by way of
alarm although we don't uh suggest that
right and they stagger into the kitchen
and um ordinarily they'd make their cup
of coffee but they're in a pseudo sleep
state yeah so it stands to reason that
they're still clearing adenosine now if
they are to drink caffeine right away
then they're as you pointed out going to
block those adenosine receptors and
there's going to be a continued buildup
of adenosine as opposed to a clearance
of adenosine so this was um part not the
entire reason but part of the rationale
for suggesting that people at least
explore delaying caffeine slightly and
then there are things like the cortisol
rise and Etc but um does that kind of
framework at least make logical sense
that doesn't mean it would hold up in a
randomized controlled trial but given
that we're talking about essentially
zero risk protocols here um what are
your thoughts on that I think it is good
advice for people to test and it's good
advice for two reasons the first is that
which you describe in some ways by
taking caffeine on early and masking
that
adenosine also caffeine can make your
brain more metabolically active which
means that you're going to build up more
adenosine during the day which means
that sleepiness is going to arrive
earlier which means that perhaps that
postprandial drop is going to be you
know harsher and you're going to perhaps
then need to self-medicate with more
caffeine to and so goes the Vicious
Cycle so I think that's one thing to
keep in mind I think that's one
hypothesis I think the second hypothesis
for me or the second reason I would
advocate for that is if you've been
using caffeine that way for a long
period of time you may also be
masking the quality of your sleep
because you wake up you immediately
medicate with caffeine and you are alert
you're awake and you think well I
looking back on my night I'm awake now
after my caffeine and now is the
important part of that sentence I'm
awake now so there's nothing wrong with
my sleep is that true maybe it is maybe
it's not maybe if you abstain from
caffeine through and you have to get
through the detox period it's not going
to this is not the right test
immediately but do it for about two
weeks and then at that point once you're
free from the detox and the withdrawal
now you're in a somewhat naive state
where you're taking your caffeine on I'm
telling you to stop caffeine you're
taking it on at 11:00 after you've woken
up let's say 7:00 in the morning at that
point we've now got this nice Clear
Window that has been consistently
happening between 7 to 11: in the
morning and I'm going to ask you now do
you feel rested restored and refreshed
and can you operate with cognitive
acumen and
skill in those first morning hours now
don't forget we've got to get past the
natural sleep and Heria period in the
first 90 minutes but after the first 90
minutes of waking up absent of caffeine
let's say by 900 a.m. in the morning are
you functioning well because if you're
not and you still think you know what I
don't feel restored by my sleep I feel
unrefreshed I want to then start asking
you let's take a look at your sleep and
let's see how we can get you to a more
refreshed state
and by using caffeine first thing in the
morning you don't give yourself the
chance to test whether or not
subjectively you sense your sleep is
good quality now you don't need to do
this forever you can just do a test for
a month and be asking that question and
if all is clear after you've got through
withdrawal and you've got past the first
90 minutes after waking up and you tell
me now in this more caffeine naive state
in the first few hours I feel rest I
feel refreshed I feel restored by my
sleep then that's great we don't need to
be concerned about your sleep so that's
the second reason I like it because it
gives you the opportunity to test out
whether or not your sleep is of good
quality or not I should also note by the
way that I mentioned I've changed my
mind on caffeine and its use and this
comes back to I just raise it because
you had said I made this suggestion and
it wasn't binary it wasn't dictatorial
you don't have to to do it I wasn't
saying that everyone needs to do it and
in fact even I will you know tweak my
schedule if I'm doing one thing in the
morning I will take on board caffeine
fairly soon if I'm not I will hold
off I came out the gate when I first
published um a book and it and I was
very dictatorial about it I and I was
very mono I was very binary you know it
was sleep is absolute and it's
it has to be this way and no other way I
was not in favor of caffeine and I was
telling people about the dangers and
there are dangers to your sleep and we
we can speak about those but it was a
little bit too
heavy-handed I've changed my mind for at
least two reasons
first that's not the way Society works
or people live so there's no amount just
like technology in saying leave your
phone outside of the room for 2 hours
before bed and don't check it for the
first 4 hours that that Genie is out the
bottle so the reason I have changed my
mind on caffeine is because if you look
at the data on on caffeine it's stunning
for
Health it on almost every metric that we
can measure drinking some degree of
caffeine is beneficial now there is a I
knew it there is a U-shaped function to
this which is once you get past sort of
three or four cups of coffee then you
start to go in the downward Direction
and things aren't so great the
contradiction however was that I was
telling people caffeine not good for
your sleep and sleep by the way is
wonderful for Health it transacts all of
these benefits that we have and will
discuss in this series but then you
compare that relative to caffeine and
caffeine transacts many of the same
health benefits so how can you explain
that Mr sleep
scientist well if you look the the data
is very clear it's not the caffeine
that's the benefit most people take on
board caffeine by way of a cup of
coffee and the Coffee Bean is Pack full
not just of caffeine it contains a
whopping dose of
antioxidants and because of our
deficient Western diets were so absent
of these
antioxidants that the humble cup of
coffee has been asked to carry the
Herculean weight of our antioxidant
needs on its shoulders so no wonder it
by itself carries such a strong Health
signal because it's providing you with
this wonderful dose of antioxidants in
addition to caffeine case in point if
you look at decaffeinated coffee you
still get the antioxidants but now now
you don't get the caffeine and lo and
behold you get many of the same health
benefits it's not the caffeine it's the
coffee itself so I think that is a a
perfectly good reason to justify
caffeine but again just like naps the
dose and the timing make the poison if
you're not someone who's sensitive to
caffeine then having a couple of cups of
caffeine and trying to step away from
the use of caffeine I would argue
somewhere between 10 to 12 hours before
you expect to go to bed depending on
your sensitivity and it is different
across people and we know that it's
genetic there is a specific um what we
call polymorphism which just means A
variation in a particular Gene and if
you look at variations in that it will
predict whether you are someone who is
very sensitive to caffeine or not very
sensitive to caffeine and it comes down
to how quickly you can essentially
metabolically remove that caffeine from
the system so if you know that you're a
very sensitive person I would probably
argue try to stay clear maybe 12 to 14
hours if you're someone who is not as
sensitive then you could maybe go to 8
hours the danger is for people who say
look I'm one of those people who is you
know really just not sensitive to
caffeine at all and I can have an
espresso with dinner and I fall asleep
fine I stay asleep fine so it's really
not a problem for me I would say that
that that may be true but the inherent
danger here is that and we've done these
studies if I give you a dose of let's
say 200 300 400 milligrams of of
caffeine in the hours before bed which
would be a large you know strong cup of
coffee or you know two espresso with
dinner some people can fall asleep and
some people stay asleep but the amount
of deep sleep that they have is
compromised in fact it can drop your
deep sleep by up to 20% now the danger
is that you wake up in the morning and
there was no signals in your sleep that
said you had problematic sleep because
you're not aware of how much deep sleep
that you had that's the reason that I
think you know sleep trackers can be
helpful in some ways but you then wake
up and you don't feel as refreshed and
restored but you don't remember having a
hard time falling asleep or staying
asleep but now you find yourself
reaching for three cups of coffee to
wake up in the morning rather than the
standard two and so goes the Vicious
Cycle
so and also you see an interesting
interrelationship we did a recent study
we just published in Wall Street Traders
it's not just caffeine use it's also
about alcohol use in the evening that
people who overmedicate with caffeine
during the day they then need something
to bring them down at night and the
principal depressant agent and
depressant not in the sense of
psychiatric depression but in the sense
of brain neural activity depression is
is alcohol so you get this classic cycle
of uppers and downers I need my uppers
during the morning my caffeine and I
need my downers at night to lull me into
sleep and it's this really interesting
trade-off which we we saw in these Wall
Street Traders so coming back to the
notion of caffeine though I am favorable
of it in terms of its health benefits I
think it's very very clear just be
mindful of the dose and be mindful of
the timing dose try to not exceed about
three cups of coffee timing understand
your sensitivity there are certain
genetic tests if you really want to get
nerdy that will tell you if you have
this sensitivity or not but you will
probably know it and therefore just say
okay I'm not that sensitive I could
probably go 8 hours or as close as 8
hours before sleep or 10 hours if you're
very sensitive 14 15 hours and keep it
to one cup um so those are the ways that
I would see moderating caffeine and
changing my my mind on caffeine which
just comes back to your point where you
were saying I made this recommendation
about caffeine I want to make sure I
modify that so people don't get confused
I certainly um needed to make a
modification to my stance on caffeine so
thank you for letting me say that which
is a long uh winded way of of getting
around it but does that help a little
bit that does help it um very much thank
you for that um addendum to the
legislature
[Laughter]
okay so you told us about the power nap
and you've told us about the caffeine
nap the so-called napino yeah what are
some other types of naps that can be
beneficial for Sleep awake cycles and
alertness so you can think about the
caffeine nap as trying to amplify it
sort of a nap plus as it were but to
your question the study that comes to
mind there was a brilliant investigation
Herculean in its study design from a
great sleep research group out in Japan
and they asked okay the nap is good the
caffeine nap may be a little bit better
but can we go
further um and so they designed a series
of studies they had five different
experimental groups and they tried to
basically create a stack a stacking
system they had across the 5 groups
there was a non naap group that's the
control then there was a nap group then
there was a nap plus caffeine group then
there was a nap Plus Cold face and cold
handwashing immediately after you wake
up I'll come back to explain why that we
think that works and then the final
group was a group that was a nap plus
bright light and again thank you uh me
offering this as the general public to
you Andrew hubman for for your light
Revolution so it was bright light at
2,000 looks immediately afterwards so
they had five groups again there was no
nap group nap group nap plus caffeine
nap plus cold hands and face washing nap
plus immediate brightlight the cold
hands and face washing is interesting I
told you before that there was this
three-part story to to the sleep wake
equation that you need to warm up to
cool down to fall asleep stay cool to
stay asleep warm up to wake up and I'm
saying warm up to wake up but use cold
water on your face and your
hands don't forget that warming up when
I say it in the morning is warming up at
the central core of your body you
reverse engineer what you did in the
evening I said warm up to cool down to
fall asleep so you warm up the periphery
to release the blood from the core and
you cool down well the reason that they
use cold hand and face
washing was because that's this vascular
surface it's the place where we can
modulate temperature quite quickly the
cold water on the face and the hands
therefore caused Vaso
constriction the the vessels and the
capillaries there they all scrunched up
and they force the blood back down into
the core of the body so the core body
temperature increase a little bit now
you also get a bit of an adrenaline shot
when you're splashing very cold water on
your hands and your face so there's some
of that too but that's the justification
so what they find firstly they were
measuring different aspects of your
cognition and your mood and your
sleepiness those were the outcome
measures to assess how did these five
different experimental groups change and
you can imag I mean this is I don't
think I would ever take on a study where
I'm doing five nap groups all within one
study it's bloody amazing so they did
the nonap group and then compared to the
nonap group The Nap group got a
wonderful benefit just as we described
and they showed benefits in their
alertness in their cognitive performance
and also they showed a reduction in
their sleepiness so Point number one on
the scoreboard for a nap then they did
the nap plus the
caffeine and sure enough you got an
added benefit to that which you already
obtained from the nap now it was nowhere
near as sizable as the benefit from the
nap so the addition of caffeine does
give you some nice benefits and I've
used this before when I've worked with
sort of professional athletes we do
instigate these nap um these caffeine
naps when needed so it did give a nice
benefit but then when they looked at the
nap Plus Cold hand and face washing and
the nap plus the bright light those also
added something to The Nap benefit now
they didn't do the sixth Group which is
really what I'm going to do some hand
waving about which is the full St stack
full fat method where they said okay
you're going to do nap plus caffeine
Plus Cold hand and face washing plus
bright light but if you were to put
those together my thought is that
they're probably additive rather than
simply just you know netting each other
out which means that if you really want
to not just do a nap or a nap plus which
would be the the Caffe nap but the nap
plus plus version you can lean into this
study and the protocol there would be
you get into bed you have your espresso
shot before you turn the light you Swig
it go down set your alarm for 20 minutes
you wake up the caffeine is kicking in
you get over the inertia you go straight
out cold hands cold face by way of cold
water and then you get immediate
daylight for 5 to 10 minutes outside and
at that point you're really in a
supercharged state so that's if you just
because I know there's probably going to
be some audience members who are willing
to give this a try or who really want to
optimize don't give me you know what is
good give me the extreme very best
that's the only suggestion I would have
based on that data I love it and
actually what you just described could
easily be um translocated to the uh the
period after uh waking from the nightly
bout of sleep although one wouldn't
ingest caffeine prior to waking up for
obvious reasons um but it would make
good sense to me to uh wake up obviously
get sunlight in one's eyes um splash
some cold water in one's face or hands
or get cold shower cold plunge um
caffeine or delay caffeine I mean it's
essentially the same set of tools and I
think it really um points to the fact
that circadian rhythm clearance of
adenosine uh temperature modulation and
of course the the way in which these
interact um are really the the levers
and and knobs to to modulate wakefulness
yeah it's it's so it there are I think
we've gone over this notion of naps but
there are ways that you can try to
manipulate the nap system still and
there are ways that you can manipulate
it even further but I like what you're
saying because it just comes back to the
fundamentals let's let's forego the the
nap conversation just go back to the
morning routine you're absolutely right
and think about the cold water and
warmart my guess is that very few people
when they go to bed
they wash their face and their hands
maybe they're probably not washing it
with cold water before they go to bed
correct they're going to be washing it
with warm water why don't they do that
and they just say well why would I
Splash cold water on my face you know
probably wakes me up you ever thought
about why it wakes you up part of it is
the you know the shot of activation but
the other part is Thermo regulation and
the opposite is what what you want to do
if anything you want to be warming your
hands and your feet and that's exactly
what you've always done you've always
medicated your sleep onset by using warm
water on your face and your hands
several times during today's discussion
we talked about polyphasic sleep um and
the different types of polyphasic sleep
that we covered are I wouldn't say
conventional but they're um conventional
is what are some of the more um esoteric
or let's call them high performance Pol
polyphasic uh strategies uh for sleep so
we've spoken about polyphasic sleep in
the natural way it occurs which is
during infancy and sleeping like a baby
means that you're sleeping in a highly
polyphasic way but probably around about
the late 1990s 2000s with the emergence
of the biohacker movement and the
Quantified
self-movement there started to become a
lot of chatter online about this notion
of polyphasic sleep and here no longer
are we infants we're now adults but
we're engaging in a pattern that is
highly
polyphasic polyphasic sleep simply by
definition again means that you're
having multiple phases of sleep within a
24-hour period And there are different
strategies so the way polyphasic sleep
in adults works is that you take the
24-hour period and you think about it
like a pie chart and then you start to
slice that pie up into these quadrants
when it comes to polyphasic sleep the
goal is to put insert multiple phases of
sleep around the 24-hour clock rather
than one single phase but the thinness
of those slices of the pie are very thin
leaving large thick slices of
wakefulness in between the notion that
being that if you were to sort of just
intersperse Little soupson of sleep in
terms of these little thin slices of
sleep you can increase the amount of
time that you're awake and you can
increase all of the benefits of a wake
so if you look at the there is a website
I think it's called the polyphasic
society and there it's not a scientific
Society like the you know psychological
the American Association for uh
psychology or medical um American
Medical Association or British medic
it's not one of those ratified certified
scientific or medical it's just society
that lives online which is great and
they make claims to suggest that
polyphasic sleep can improve aspects of
your mood it can improve aspects of your
productivity it can maybe even improve
aspects of Health I think sometimes
there are claims that it can help with
lifespan and there are a number of
different schedules that they will
describe to you and that you can find
out there of polyphasic sleep there is
is the first one that probably people
have heard of is called the uberman
schedule and by the way there is no h at
the start of that it is simply you I
know it's not this man sitting across
from me who has anything to do with this
schedule and after we discuss the data
he will um reassert that very same fact
then there's something called the
Everyman shedule and then there is the
triphasic schedule and there's lots of
different other flavors of this the
differences between them are in how you
split up that pie chart and how much you
assign to little thin slices of sleep
versus longer periods of wake and how
many of those you insert but they all
follow the same pattern if you look at
the literature however it didn't begin
with the biohacker movement the first
description I can find in the human
record comes from Time Magazine an issue
in
1943 and they describe the protocol of
at the time a fantastic very interesting
designer a guy called book Minster
Fuller and he created a design principle
and that design principle was called the
daxian principle the daxian principle
was principally used initially to build
unique building structures and it uses
this notion of different sort of almost
spokes that interconnect in a central
Hub that create a self-supporting
structure are the most obvious have you
ever been to one of those geodesic domes
and inside you go in it's like a
botanical garden and it's all tropical
despite you being in a let's say being
in England in London and is beautifully
tropical inside of that that structure
that sort of latis structure that comes
in part from his Design This was the
daxian principle and he scaled it to
different things the daxian car the
daxian house the daxian Dome it
fascinating
but he was no fan of sleep and he saw
sleep as a rather significant waste of
time when just like the rest of his
daxian principle he could be harnessing
more efficiency out of the system with
less structure and here less sleep
structure inserted into his 24-hour
period so he was the first one to
describe his schedule and it was called
the daxian schedule of polyphasic sleep
so it may have been a practice earlier
in the record but that's the earliest
one I can find so let's come back to the
claims of polyphasic sleep that it could
improve let's say your mood or your
cognition or your productivity or your
health the a group of scientists at
Harvard some of my old colleagues um
from Harvard they looked at all of the
literature on all of the stes that were
polyphasic like or testing this
claim and the first thing that they
found was to their claims of improved
cognition productivity mood as well as
health they found no supportive evidence
that polyphasic sleep was helpful then
they turned the tables and they said
well could it be hurtful and in fact
that's exactly what they found firstly
the total amount of sleep that you get
on any one of those schedules is
decreased significantly now of course
that's the goal the quality of sleep
that you get though is miserable your
sleep efficiency even when you're having
these short periods of time especially
during the waking hours is very poor
it's not a type of even short sleep that
you would wish for third they found that
it would reduce your REM sleep amounts
so that was the first set of findings
your sleep is no better if anything it's
significantly worse and then they
started to find that there were
significant impairments in many of those
things impairments in cognition in
judgment making and decision- making
impairment in mood and some aspects of
impairment in metabolic Health
particularly glucose
regulation so when it comes to
polyphasic sleep sleeping like a baby if
you're an adult seems to be a rather
unwise piece of advice now yeah I mean
it probably goes along with eating baby
food drinking breast milk and um and uh
having somebody else uh clothe and
change you as an adult it's probably uh
not advisable
it doesn't seem to be at least supported
by the data and again I want to be so
careful here and you're very careful too
I'm not here to necessarily tell anyone
absolutely how to live their life I'm
just a scientist and all I can do is
give you the information just as you do
and then it's up to you to make the best
decisions that you wish to make all I
would say is that I would hope that as
long as you're not hurting yourself and
harming your health and you're not
hurting other people then and it makes
you happy then I say whatever it is in
life good luck I I embrace it I always
say uh do as do as you wish but know
what you're
doing and don't hurt yourself or anybody
else can you get me that T-shirt and I
will wear it five days through Tuesday
so here in this regard though I would
say the evidence would suggest that
maybe you're compromising your health
and your Wellness but that's your choice
voice and I understand it so again no
judgment to the question however of as
long as you're not hurting other people
here I would say that there is a pause
of a caution because what we know is
that when you're not getting sufficient
sleep I described all of the health
consequences in the first episode
there's another danger here which is
road traffic accidents and we describe
these micro sleeps that happen and why
car accidents that are caused by
sleepiness can be so catastrophic
there's a very interesting study that
was done where they looked at people
getting less than 6 hours of sleep for
several nights and they put them into a
driving simulator and they asked what is
the probability that you have a crash or
an off-road event and sleeping less than
6 hours a night resulted in a 30%
increase in you getting into a car
crash now the AAA release some data
showing that when you get down to 5
hours of sleep there is I think it's
something like two Three Times Higher
likelihood of an accident based on real
data and then when you were on 4 hours
of sleep it was close to a 10 times
greater risk so in other words the less
and less sleep that you get it's not a
linear increase in your risk of a car
accident it's an exponential increase so
I bring this back to polyphasic sleep
because I don't know you know think
about that 30% study let's not go to the
extreme just less than 6 hours of sleep
if this evening you call a taxi and it
turns out two taxis turned up and
outside of your door I said look one of
these two ta you can choose either one
of them but I'll just tell you that one
of these taxis has a 30% higher
likelihood of getting in a crash
relative to the other and it's this one
on the right which would you like to
pick which would you like to put your
wife and children in to S it's very
obvious so I rais that question just to
be mindful no one would wish to cause
harm on someone else to C carry the harm
of someone else by way of your own doing
on your shoulders for the rest of your
life is not one I would wish for and
it's not one that you would wish for
that's the only cautionary note but
other than that I would say you know
sort of live life to the full well that
brings us to the conclusion of yet
another incredible Voyage into the
landscape of sleep most notably on the
different phases monophasic biphasic and
polyphasic sleep
and naps and caffeine and all of their
interactions these are such important
topics at the level of Concepts the
level of mechanisms and as you've also
beautifully described at the level of
protocols that is actionable tools that
people can apply so thank you ever so
much Matt for taking us even further
along this Voyage I'll just remind
people that episodes one and two of this
series that U Matt is uh so generously
providing information about sleep for us
are out and those can be accessed
through links in the show note captions
um those fill in yet other mechanisms
and aspects of sleep and I'm also
particularly excited for the fourth
installment in this series coming up
about the relationship between sleep
memory and creativity so just incredibly
important topics relevant to everybody I
also just want to make note that I
really appreciate you highlighting some
of the develop velopmental shifts that
occur with sleep I often get questions
about um you know sleep in children and
babies and uh elderly adults as well as
um all the ages in between and you've
just um built this incredible tapestry
of of information for people to think
about and act upon should they choose so
thank you Matt ever so much and I look
forward to episode four Andrew thank you
it is such a privilege and it remains
just my absolute Delight to be here with
you thank you thank you for joining me
for today's episode with Dr Matthew
Walker to learn more about Dr Walker's
research and to learn more about his
book and his social media handles please
see the links in our show note captions
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